Traffic Group Signals | The Tortoise and the Hare – Modelling Road User Micro-Journeys To Determine Accurate Intergreen Times

How can we make journeys through road works safer for all road users?

The selection of appropriate red times (or ‘intergreens’) is an essential safety consideration for any traffic signal design, whether permanent or temporary. If the times chosen are too short, collisions or near-misses could occur. Times that are too long impact efficiency and can cause a reduction in signal compliance, with drivers running the red light. Dr Darren Hudson asks does current Chapter 8 and Chapter 6 timing guidance work for all road users in temporary traffic management environments?

Historically, the Traffic Management industry has adopted highly simplistic phase-based signalling, that services just one phase at a time. Conventional signals are typically easy to set up, using red times based on clearance or datum times that are configured at the roadside. This high degree of flexibility comes at the expense of signalling efficiency, safety and a high degree of cost, as many sites require an operative to be present to manage traffic volumes by adapting signal timings.

The industry looks to both Chapter 8 and Chapter 6 for guidance on setting phase-based and stage-based signal timings. The guidance simplifies the process significantly, however, in doing so, the way in which a specific road layout affects each vehicle type is not fully taken into account. This is more of an issue at roadworks sites where vehicles travel longer distances through signals and may also encounter areas of single-lane shuttle operation.

Much greater efficiency is possible by using a full intergreen matrix, yet Chapter 6 guidance is not optimised for use in a temporary traffic management environment, nor is it practical to configure sophisticated timing calculations at the roadside.

Traffic Group Signals have responded to these shortcomings with two groundbreaking signalling products, Evo1 and Metro, which both support stage-based signalling with a full intergreen matrix, configured by a sophisticated software application, Signal Studio.

In our recently published paper, The Tortoise and the Hare – Modelling Road User Micro-Journeys To Determine Accurate Intergreen Times, Dr Darren Hudson explores a new method of calculating Intergreen times that aspires to create safe and efficient intergreen times for all users.

Using our proprietary software, Signal Studio, our new intergreen measurement feature takes into account the fastest and slowest road users, the geometry of the road and the path travelled through the site to provide highly accurate timings. This pioneering physics model ensures sufficient time is given to the most vulnerable road users, making for a much safer roadworks environment.

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